I was looking at the Monarchy SM70 amp. This is a stereo amp that is claimed to be 40watts, Class A and Single Ended. Those last two features would be two strikes against it being efficient
However what confuses me is that the heat sinks are at most only about 4 by 11 inches (each on a side). There is no fan.
When I look at the good work that is being done here, I see much more massive heat sinking for much less output. Is this manufacturer playing a "numbers game" about the performance and design. I am asking in this forum, since the responses are more knowledgeable and honest.
Thanks for your thoughts
However what confuses me is that the heat sinks are at most only about 4 by 11 inches (each on a side). There is no fan.
When I look at the good work that is being done here, I see much more massive heat sinking for much less output. Is this manufacturer playing a "numbers game" about the performance and design. I am asking in this forum, since the responses are more knowledgeable and honest.
Thanks for your thoughts
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A clarification
Let me clarify. I am referring to the SM70 (not the SM70Pro).
You are correct, the output is 25watts/channel at 8 Ohms.
Printed on the amplifier cabinet it clearly reads "Pure Class A"
The Single Ended claim I can no longer find on the website; however, they do list magazine reviews where the reviewers refer to it as "single ended". The Monarchy website has these reviews , but perhaps they are not responsible if the magazine got it wrong.
In either case, even at the claimed 25 watts, the heat sinking seems small. That is what I am confused about.
Thanks
Let me clarify. I am referring to the SM70 (not the SM70Pro).
You are correct, the output is 25watts/channel at 8 Ohms.
Printed on the amplifier cabinet it clearly reads "Pure Class A"
The Single Ended claim I can no longer find on the website; however, they do list magazine reviews where the reviewers refer to it as "single ended". The Monarchy website has these reviews , but perhaps they are not responsible if the magazine got it wrong.
In either case, even at the claimed 25 watts, the heat sinking seems small. That is what I am confused about.
Thanks
The very large "Pure Class A" on the front plate would be an indication 
But for the single endedness, yeah, I doubt.
Well 25 WRMS in 8 Ohms is 35W peak, so this gives 2A peak and 17V peak, a pure class A amp with 2A idle current and (say) +/- 20V supplies would dissipate 80W per channel... you'd need a 0.5°C/W heatsink which is compatible with the dimensions you quote (9 cm * 30 cm). I have a heatsink in my supplier catalog which is 10cmx30cmx4cm and listed as 0.3 °C/W.
But for the single endedness, yeah, I doubt.
Well 25 WRMS in 8 Ohms is 35W peak, so this gives 2A peak and 17V peak, a pure class A amp with 2A idle current and (say) +/- 20V supplies would dissipate 80W per channel... you'd need a 0.5°C/W heatsink which is compatible with the dimensions you quote (9 cm * 30 cm). I have a heatsink in my supplier catalog which is 10cmx30cmx4cm and listed as 0.3 °C/W.
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